Growth and magnetic properties of ferromagnetic Co nanorods filled inside carbon nanotubes towards nanoscale spintronics

We synthesize Co nanorod filled inside multi-walled CNTs (MWCNTs) by microwave plasma enhanced chemical vapor deposition (MPECVD) and utilize off-axis electron holography to observe the remanent states of the filled metal nanorod inside MWCNTs at room. The MWCNTs grew up to 100-110 nm in diameter and 1.5-1.7 μm in length. The typical bright-field transmission electron microscope (TEM) images revealed both Co/Pd multisegment nanorod and Co nanorod filled inside MWCNTs on the same substrate. We have also performed energy-dispersive X-ray spectrometer (EDS) measurements to characterize the composition of metal filled inside MWCNTs. Based on high-resolution TEM measurements, we observed the face-centered-cubic (fcc) Co filled inside MWCNT. The component of magnetic induction was then measured to be 1.2±0.1 T, which is lower than the expected saturation magnetization of fcc Co of 1.7 T. The partial oxidation of the ferromagnetic metal during the process and the magnetization direction may play an important role in the determination of the quality of the remanent states. © 2008 IEEE.

A bone remodelling model coupling micro-damage growth and repair by 3D BMU-activity.

Bone as most of living tissues is able, during its entire lifetime, to adapt its internal microstructure and subsequently its associated mechanical properties to its specific mechanical and physiological environment in a process commonly known as bone remodelling. Bone is therefore continuously renewed and micro-damage, accumulated by fatigue or creep, is removed minimizing the risk of fracture. Nevertheless, bone is not always able to repair itself completely. Actually, if bone repairing function is slower than micro-damage accumulation, a type of bone fracture, usually known as "stress fracture", can finally evolve. In this paper, we propose a bone remodelling continuous model able to simulate micro-damage growth and repair in a coupled way and able therefore to predict the occurrence of "stress fractures". The biological bone remodelling process is modelled in terms of equations that describe the activity of basic multicellular units. The predicted results show a good correspondence with experimental and clinical data. For example, in disuse, bone porosity increases until an equilibrium situation is achieved. In overloading, bone porosity decreases unless the damage rate is so high that causes resorption or "stress fracture".

Age, growth and mortality of the toadfish, Halobatrachus didactylus (Schneider, 1801) (Pisces: Batrachoididae), in the Bay of Cádiz (southwestern Spain)

Age, growth and mortality of the toadfish, Halobatrachus didactylus, were determined by examination of the whole sagittal otoliths of fish sampled in the Bay of Cádiz (southwestern Spain) from March 1999 to March 2000. A total of 844 specimens (425 males, 416 females, and 3 of indeterminate sex), ranging from 95 to 470 mm in total length were examined. Eighty-nine percent of the otoliths could be read allowing an age estimation. The opaque zone was formed between April and May coincident with the maximum reproductive peak, while the translucent zone formed mainly in summer-fall (June to December). Maximum ages for males and females were 12 and 10 years, respectively. The samples were dominated by 2- to 6-year-old specimens. Males matured at an age of approximately 2 years and females at 3 years. Fish total length and otolith radius were closely related. The von Bertalanffy growth curve was used to describe growth. The parameters were derived from back-calculated length-at-age. Significant differences in the growth parameters were found between sexes. Although the growth analysis revealed that this species is slow-growing, males reached larger sizes than females. Females appeared to experience higher natural mortality rates than males.

Sex-specific growth and mortality, spawning season, and female maturation of the stripey bass (Lutjanus carponotatus) on the Great Barrrier Reef

Sex-specific demography and reproductive biology of stripey bass (Lutjanus carponotatus) (also known as Spanish flag snapper, FAO) were examined at the Palm and Lizard island groups, Great Barrier Reef (GBR).Total mortality rates were similar between the sexes. Males had larger L∞ at both island groups and Lizard Island group fish had larger overall L∞. Female:male sex ratios were 1.3 and 1.1 at the Palm and Lizard island groups, respectively. The former is statistically different from 1, but is unlikely significantly different in a biological sense. Females matured on average at 2 years of age and 190 mm fork length at both locations. Female gonadal lipid body indices peaked from August through October, preceding peak gonadosomatic indices in October, November, and December that were twice as great as in any other month. However, ovarian staging revealed 50% or more ovaries were ripe from September through February, suggesting a more protracted spawning season and highlighting the different interpretations that can arise between gonad weight and gonad staging methods. Gonadosomatic index increases slightly with body size and larger fish have a longer average spawning season, which suggests that larger fish produce greater relative reproductive output. Lizard Island group females had ovaries nearly twice as large as Palm Island group females at a given body size. However, it is unclear whether this reflects spatial differences akin to those observed in growth or effects of sampling Lizard Island group fish closer to their date of spawning. These results support an existing 250 mm minimum size limit for L. carponotatus on the GBR, as well as the timing of a proposed October through December spawning closure for the fishery. The results also caution against assessing reef-fish stocks without reference to sex-, size-, and location-specific biological traits.